Apple watch
I really want an Apple Watch but do I need a phone to use it?
Apple Watch SE
Question marked as
Yes, Watch is an iphone accessory.
You can use either your own iphone, or you can pair to your parent's or another family member's iphone but with limited functions and that would need to be a cellular model.
Read the following link, which explains how to set up Apple Watch using Family Setup to your iPhone -->
Set up Apple Watch for a family member - Apple Support